How do I fix melds 'Cannot import: GTK+' error caused by missing 'gi.repository'?

Question

I've recently started learning GTK+ development and installed some new packages (I don't remember which ones). Now the merge tool meld doesn't work any more:

Cannot import: GTK+
No module named repository

This is caused by line 155 of the meld executable:

from gi.repository import Gtk

Note that I can import gi.repository in Python 3, but it is not so simple to convert meld to Python 3.

How can I fix it?

What I've tried:

• sudo apt-get install python-gobject: Was already installed (source)

Answer 1

I had the gi package installed:

$ sudo pip uninstall gi

fixed my problem.